开封地区奶牛十二指肠贾第虫流行情况及多位点基因分型的研究

Prevalence and multilocus genotyping of Giardia duodenalis in dairy cattle in Kaifeng,China

为了解河南省开封地区奶牛十二指肠贾第虫的感染情况、流行特点及其基因型分布特征,从2012年11月—2014年3月对开封地区4个奶牛养殖场和5个奶牛养殖小区进行采样,共采集样品622份。采用卢戈氏碘液染色法检查新鲜粪便样本的十二指肠贾第虫包囊。基于SSU rRNA、TPI和GDH基因位点的多位点分析法对奶牛阳性贾第虫分离株进行了种类鉴定。结果显示,奶牛十二指肠贾第虫阳性率为3.4%(21/622);断奶前犊牛感染率最高(14.5%),其次为断奶后犊牛(2.4%),育成牛和成年牛均未发现感染(P<0.01);规模化养殖条件下奶牛十二指肠贾第虫感染率(5.0%)显著高于散养条件(0.5%)(P<0.01)。基于SSU rRNA、TPI和GDH基因位点扩增,在21个阳性样品中分别扩增出19个、16个和15个目的片段。多位点基因序列分析显示该地区奶牛十二指肠贾第虫基因型均为集聚体E,其多位点序列多态性变异较小。上述研究结果表明,开封地区奶牛所携带十二指肠贾第虫人兽共患风险性较低。

To understand the prevalence and molecular characteristics of Giardia duodenalis in dairy cattle in Kaifeng, Henan Province, Central China, a total of 622 dairy cattle fecal samples were randomly collected in 4 different intensive farms and 5 raising plots in Kaifeng from November 2012 until March 2014. The collected fresh stool samples were examined for the presence of G.duodenalis cyst with Lugol＇s iodine staining.The assemblages and subtypes of G.duodenalis positive isolates were identified with multilocus genotyping based on SSU rRNA,TPI and GDH genes. The results showed that 3.4%（21/622） was positive for G.duodenalis infection, with pre-weaned calves having the highest infection rate（14.5%）, followed by post-weaned calves（2.4%）（P〈0.01）. No infection was found on heifers and adults. And the prevalence on condition of large-scale breeding was significantly higher than that of rural household＇s scatter breeding（5.0% versus 0.5%, respectively）（P〈0.01）. Total 19, 16 and 15 of 21 positive G.duodenalis isolates were successfully amplified based on SSU rRNA,TPI and GDH gene,respectively. Multilocus genotyping showed that one assemblage was detected： assemblage E.Sequencepolymorphism variation was low between G.duodenalis assemblage E.The results suggest that the G.duodenalis carried by dairy cattle in this district may be a minimal zoonotic threat.